Pesonally, I think it is a bug in the game. She went down without any trouble; a gentle slope (what I see as gentle, but I live in hilly country, foothills of the Appalachcian Mt.) it leveled out for a short bit then another short slope. Not sure how many times it slopped, I kept finding gems and metals and sites to excavate.
Did an angled climb and still couldn't go up; which works on another slope she can't climb straight up.
It is the area near the Great Wall, so I think it is a trap area, full of bugs. She was struck there all night, yelling, her energy bar going red. The next morning, with plenty of light to see, I still couldn't find a way out. I was doing an adventure of finding mercury and has a lucky trip, a LOT of gems, metals, rocks and sites to excavate and lost it all when I had to restart from last save. Which taught me the hard way to save often, especially when I have collected some goodies or do something that seems to have any possibility to be a trap.